Automatic dishwashing detergents are generally recognized as a class of detergent compositions distinct from those used for fabric washing or water treatment. Automatic dishwashing detergents are expected by users to produce a spotless and film-free appearance on washed items after a complete cleaning cycle.
Phosphate-free compositions rely on non-phosphate builders, such as salts of citrate, carbonate, silicate, disilicate, bicarbonate, aminocarboxylates and others to sequester calcium and magnesium from hard water and block them from leaving an insoluble visible deposit on the dishware following drying.
The most commonly used aminocarboxylate builder in today's phosphate-free automatic dishwashing detergents is methylglycinediacetic acid (MGDA). Among the negatives of MGDA is that formulations containing this material are corrosive to glass and metal, and can often lead to pitting or discoloration on silverware and/or the metal components of a dishwasher.
Glutamic acid-N,N-diacetic acid (GLDA) is another aminocarboxylate builder that is used in phosphate-free automatic dishwashing detergents. GLDA also exhibits various shortcomings, including providing cleaning performance, such as spotless and film-free appearance on washed items, that is less than optimal.
Compositions that exhibit improved properties in automatic dishwashing would be an advance in the industry.